Correction fluids are used for correcting handwritten, typewritten or photocopied markings on paper. Generally correction fluids are applied to a paper surface in liquid form. After application, correction fluids should dry relatively quickly to provide a film which can effectively cover erroneous markings on the surface and can receive a corrected marking. It is required that the dried film be strongly bonded to the paper surface, and sufficiently flexible that the film will not be removed under normal conditions. It is also desired that the composition dry at a rapid rate. Other desired performance characteristics include good storage stability, and flow and viscosity characteristics which permit easy and even application of the fluid.
Correction fluids typically contain an acrylic binding resin, and an opacifying pigment, usually titanium dioxide, dispersed in a solvent. Halogenated hydrocarbon solvents have been the solvents of choice because of their evaporation rates which provide correction fluids which dry rapidly and completely. Additionally, they do not interact with typewritten markings to cause unacceptable bleeding. Also, they can effectively dissolve those film forming polymeric materials which provide durable but flexible films without causing excessive cockling or distortion of paper surfaces. Despite their recognized advantages when used as correction fluid solvents, the use of halogenated hydrocarbon solvents has become a matter of increased concern primarily because of their adverse effect on the environment (stratospheric ozone depletion) and also because of their potential adverse effect on health through solvent abuse. Accordingly, the elimination of halogenated hydrocarbon solvents from correction fluids is desired.
Non-halogenated hydrocarbon-free correction fluids are disclosed in U.S. Pat. No. 5,199,976 and PCT App. WO 93/21261. U.S. Pat. No. 5,199,976 discloses a correction fluid containing a volatile, nonhalogenated solvent, a vinyl toluene-butadiene copolymer as the polymeric-film forming material, a dispersing agent and an opacifying agent. While halogens have been removed from the correction fluid, the volatile solvents cause health and environmental problems.
PCT App. WO 93/21261 discloses a correction fluid containing a volatile, nonhalogenated solvent, an isobutyl methacrylate copolymer as the polymeric-film forming material, a plasticizer, and an opacifying agent. While halogens have been removed from the correction fluid, the volatile solvents cause health and environmental problems. Accordingly, the elimination of volatile organic solvents (VOC's) from correction fluids is desired.
UK Pat. App. GB 2 058 110 A discloses an aqueous correction fluid containing a stable emulsion of a water-dispersed, water-insoluble acrylic resin as a binder for the masking pigment. The correction fluid forms smooth, highly opaque, and flexible masking coatings. However, the correction fluid has an unacceptable drying time due to the large amount of water.